Mon, 23 Jan 2012 20:36:16 +0100
7132311: G1: assert((s == klass->oop_size(this)) || (Universe::heap()->is_gc_active() && ((is_typeArray()...
Summary: Move the check for when to call collect() to before we do a humongous object allocation
Reviewed-by: stefank, tonyp
1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP
28 #include "gc_implementation/g1/collectionSetChooser.hpp"
29 #include "gc_implementation/g1/g1MMUTracker.hpp"
30 #include "memory/collectorPolicy.hpp"
32 // A G1CollectorPolicy makes policy decisions that determine the
33 // characteristics of the collector. Examples include:
34 // * choice of collection set.
35 // * when to collect.
37 class HeapRegion;
38 class CollectionSetChooser;
40 // Yes, this is a bit unpleasant... but it saves replicating the same thing
41 // over and over again and introducing subtle problems through small typos and
42 // cutting and pasting mistakes. The macros below introduces a number
43 // sequnce into the following two classes and the methods that access it.
45 #define define_num_seq(name) \
46 private: \
47 NumberSeq _all_##name##_times_ms; \
48 public: \
49 void record_##name##_time_ms(double ms) { \
50 _all_##name##_times_ms.add(ms); \
51 } \
52 NumberSeq* get_##name##_seq() { \
53 return &_all_##name##_times_ms; \
54 }
56 class MainBodySummary;
58 class PauseSummary: public CHeapObj {
59 define_num_seq(total)
60 define_num_seq(other)
62 public:
63 virtual MainBodySummary* main_body_summary() { return NULL; }
64 };
66 class MainBodySummary: public CHeapObj {
67 define_num_seq(satb_drain) // optional
68 define_num_seq(parallel) // parallel only
69 define_num_seq(ext_root_scan)
70 define_num_seq(satb_filtering)
71 define_num_seq(update_rs)
72 define_num_seq(scan_rs)
73 define_num_seq(obj_copy)
74 define_num_seq(termination) // parallel only
75 define_num_seq(parallel_other) // parallel only
76 define_num_seq(mark_closure)
77 define_num_seq(clear_ct)
78 };
80 class Summary: public PauseSummary,
81 public MainBodySummary {
82 public:
83 virtual MainBodySummary* main_body_summary() { return this; }
84 };
86 // There are three command line options related to the young gen size:
87 // NewSize, MaxNewSize and NewRatio (There is also -Xmn, but that is
88 // just a short form for NewSize==MaxNewSize). G1 will use its internal
89 // heuristics to calculate the actual young gen size, so these options
90 // basically only limit the range within which G1 can pick a young gen
91 // size. Also, these are general options taking byte sizes. G1 will
92 // internally work with a number of regions instead. So, some rounding
93 // will occur.
94 //
95 // If nothing related to the the young gen size is set on the command
96 // line we should allow the young gen to be between
97 // G1DefaultMinNewGenPercent and G1DefaultMaxNewGenPercent of the
98 // heap size. This means that every time the heap size changes the
99 // limits for the young gen size will be updated.
100 //
101 // If only -XX:NewSize is set we should use the specified value as the
102 // minimum size for young gen. Still using G1DefaultMaxNewGenPercent
103 // of the heap as maximum.
104 //
105 // If only -XX:MaxNewSize is set we should use the specified value as the
106 // maximum size for young gen. Still using G1DefaultMinNewGenPercent
107 // of the heap as minimum.
108 //
109 // If -XX:NewSize and -XX:MaxNewSize are both specified we use these values.
110 // No updates when the heap size changes. There is a special case when
111 // NewSize==MaxNewSize. This is interpreted as "fixed" and will use a
112 // different heuristic for calculating the collection set when we do mixed
113 // collection.
114 //
115 // If only -XX:NewRatio is set we should use the specified ratio of the heap
116 // as both min and max. This will be interpreted as "fixed" just like the
117 // NewSize==MaxNewSize case above. But we will update the min and max
118 // everytime the heap size changes.
119 //
120 // NewSize and MaxNewSize override NewRatio. So, NewRatio is ignored if it is
121 // combined with either NewSize or MaxNewSize. (A warning message is printed.)
122 class G1YoungGenSizer : public CHeapObj {
123 private:
124 enum SizerKind {
125 SizerDefaults,
126 SizerNewSizeOnly,
127 SizerMaxNewSizeOnly,
128 SizerMaxAndNewSize,
129 SizerNewRatio
130 };
131 SizerKind _sizer_kind;
132 size_t _min_desired_young_length;
133 size_t _max_desired_young_length;
134 bool _adaptive_size;
135 size_t calculate_default_min_length(size_t new_number_of_heap_regions);
136 size_t calculate_default_max_length(size_t new_number_of_heap_regions);
138 public:
139 G1YoungGenSizer();
140 void heap_size_changed(size_t new_number_of_heap_regions);
141 size_t min_desired_young_length() {
142 return _min_desired_young_length;
143 }
144 size_t max_desired_young_length() {
145 return _max_desired_young_length;
146 }
147 bool adaptive_young_list_length() {
148 return _adaptive_size;
149 }
150 };
152 class G1CollectorPolicy: public CollectorPolicy {
153 private:
154 // either equal to the number of parallel threads, if ParallelGCThreads
155 // has been set, or 1 otherwise
156 int _parallel_gc_threads;
158 // The number of GC threads currently active.
159 uintx _no_of_gc_threads;
161 enum SomePrivateConstants {
162 NumPrevPausesForHeuristics = 10
163 };
165 G1MMUTracker* _mmu_tracker;
167 void initialize_flags();
169 void initialize_all() {
170 initialize_flags();
171 initialize_size_info();
172 initialize_perm_generation(PermGen::MarkSweepCompact);
173 }
175 CollectionSetChooser* _collectionSetChooser;
177 double _cur_collection_start_sec;
178 size_t _cur_collection_pause_used_at_start_bytes;
179 size_t _cur_collection_pause_used_regions_at_start;
180 double _cur_collection_par_time_ms;
181 double _cur_satb_drain_time_ms;
182 double _cur_clear_ct_time_ms;
183 double _cur_ref_proc_time_ms;
184 double _cur_ref_enq_time_ms;
186 #ifndef PRODUCT
187 // Card Table Count Cache stats
188 double _min_clear_cc_time_ms; // min
189 double _max_clear_cc_time_ms; // max
190 double _cur_clear_cc_time_ms; // clearing time during current pause
191 double _cum_clear_cc_time_ms; // cummulative clearing time
192 jlong _num_cc_clears; // number of times the card count cache has been cleared
193 #endif
195 // These exclude marking times.
196 TruncatedSeq* _recent_gc_times_ms;
198 TruncatedSeq* _concurrent_mark_remark_times_ms;
199 TruncatedSeq* _concurrent_mark_cleanup_times_ms;
201 Summary* _summary;
203 NumberSeq* _all_pause_times_ms;
204 NumberSeq* _all_full_gc_times_ms;
205 double _stop_world_start;
206 NumberSeq* _all_stop_world_times_ms;
207 NumberSeq* _all_yield_times_ms;
209 int _aux_num;
210 NumberSeq* _all_aux_times_ms;
211 double* _cur_aux_start_times_ms;
212 double* _cur_aux_times_ms;
213 bool* _cur_aux_times_set;
215 double* _par_last_gc_worker_start_times_ms;
216 double* _par_last_ext_root_scan_times_ms;
217 double* _par_last_satb_filtering_times_ms;
218 double* _par_last_update_rs_times_ms;
219 double* _par_last_update_rs_processed_buffers;
220 double* _par_last_scan_rs_times_ms;
221 double* _par_last_obj_copy_times_ms;
222 double* _par_last_termination_times_ms;
223 double* _par_last_termination_attempts;
224 double* _par_last_gc_worker_end_times_ms;
225 double* _par_last_gc_worker_times_ms;
227 // Each workers 'other' time i.e. the elapsed time of the parallel
228 // phase of the pause minus the sum of the individual sub-phase
229 // times for a given worker thread.
230 double* _par_last_gc_worker_other_times_ms;
232 // indicates whether we are in young or mixed GC mode
233 bool _gcs_are_young;
235 size_t _young_list_target_length;
236 size_t _young_list_fixed_length;
237 size_t _prev_eden_capacity; // used for logging
239 // The max number of regions we can extend the eden by while the GC
240 // locker is active. This should be >= _young_list_target_length;
241 size_t _young_list_max_length;
243 bool _last_gc_was_young;
245 unsigned _young_pause_num;
246 unsigned _mixed_pause_num;
248 bool _during_marking;
249 bool _in_marking_window;
250 bool _in_marking_window_im;
252 SurvRateGroup* _short_lived_surv_rate_group;
253 SurvRateGroup* _survivor_surv_rate_group;
254 // add here any more surv rate groups
256 double _gc_overhead_perc;
258 double _reserve_factor;
259 size_t _reserve_regions;
261 bool during_marking() {
262 return _during_marking;
263 }
265 private:
266 enum PredictionConstants {
267 TruncatedSeqLength = 10
268 };
270 TruncatedSeq* _alloc_rate_ms_seq;
271 double _prev_collection_pause_end_ms;
273 TruncatedSeq* _pending_card_diff_seq;
274 TruncatedSeq* _rs_length_diff_seq;
275 TruncatedSeq* _cost_per_card_ms_seq;
276 TruncatedSeq* _young_cards_per_entry_ratio_seq;
277 TruncatedSeq* _mixed_cards_per_entry_ratio_seq;
278 TruncatedSeq* _cost_per_entry_ms_seq;
279 TruncatedSeq* _mixed_cost_per_entry_ms_seq;
280 TruncatedSeq* _cost_per_byte_ms_seq;
281 TruncatedSeq* _constant_other_time_ms_seq;
282 TruncatedSeq* _young_other_cost_per_region_ms_seq;
283 TruncatedSeq* _non_young_other_cost_per_region_ms_seq;
285 TruncatedSeq* _pending_cards_seq;
286 TruncatedSeq* _rs_lengths_seq;
288 TruncatedSeq* _cost_per_byte_ms_during_cm_seq;
290 TruncatedSeq* _young_gc_eff_seq;
292 G1YoungGenSizer* _young_gen_sizer;
294 size_t _eden_cset_region_length;
295 size_t _survivor_cset_region_length;
296 size_t _old_cset_region_length;
298 void init_cset_region_lengths(size_t eden_cset_region_length,
299 size_t survivor_cset_region_length);
301 size_t eden_cset_region_length() { return _eden_cset_region_length; }
302 size_t survivor_cset_region_length() { return _survivor_cset_region_length; }
303 size_t old_cset_region_length() { return _old_cset_region_length; }
305 size_t _free_regions_at_end_of_collection;
307 size_t _recorded_rs_lengths;
308 size_t _max_rs_lengths;
310 double _recorded_young_free_cset_time_ms;
311 double _recorded_non_young_free_cset_time_ms;
313 double _sigma;
314 double _expensive_region_limit_ms;
316 size_t _rs_lengths_prediction;
318 size_t _known_garbage_bytes;
319 double _known_garbage_ratio;
321 double sigma() {
322 return _sigma;
323 }
325 // A function that prevents us putting too much stock in small sample
326 // sets. Returns a number between 2.0 and 1.0, depending on the number
327 // of samples. 5 or more samples yields one; fewer scales linearly from
328 // 2.0 at 1 sample to 1.0 at 5.
329 double confidence_factor(int samples) {
330 if (samples > 4) return 1.0;
331 else return 1.0 + sigma() * ((double)(5 - samples))/2.0;
332 }
334 double get_new_neg_prediction(TruncatedSeq* seq) {
335 return seq->davg() - sigma() * seq->dsd();
336 }
338 #ifndef PRODUCT
339 bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);
340 #endif // PRODUCT
342 void adjust_concurrent_refinement(double update_rs_time,
343 double update_rs_processed_buffers,
344 double goal_ms);
346 uintx no_of_gc_threads() { return _no_of_gc_threads; }
347 void set_no_of_gc_threads(uintx v) { _no_of_gc_threads = v; }
349 double _pause_time_target_ms;
350 double _recorded_young_cset_choice_time_ms;
351 double _recorded_non_young_cset_choice_time_ms;
352 size_t _pending_cards;
353 size_t _max_pending_cards;
355 public:
356 // Accessors
358 void set_region_eden(HeapRegion* hr, int young_index_in_cset) {
359 hr->set_young();
360 hr->install_surv_rate_group(_short_lived_surv_rate_group);
361 hr->set_young_index_in_cset(young_index_in_cset);
362 }
364 void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {
365 assert(hr->is_young() && hr->is_survivor(), "pre-condition");
366 hr->install_surv_rate_group(_survivor_surv_rate_group);
367 hr->set_young_index_in_cset(young_index_in_cset);
368 }
370 #ifndef PRODUCT
371 bool verify_young_ages();
372 #endif // PRODUCT
374 double get_new_prediction(TruncatedSeq* seq) {
375 return MAX2(seq->davg() + sigma() * seq->dsd(),
376 seq->davg() * confidence_factor(seq->num()));
377 }
379 void record_max_rs_lengths(size_t rs_lengths) {
380 _max_rs_lengths = rs_lengths;
381 }
383 size_t predict_pending_card_diff() {
384 double prediction = get_new_neg_prediction(_pending_card_diff_seq);
385 if (prediction < 0.00001) {
386 return 0;
387 } else {
388 return (size_t) prediction;
389 }
390 }
392 size_t predict_pending_cards() {
393 size_t max_pending_card_num = _g1->max_pending_card_num();
394 size_t diff = predict_pending_card_diff();
395 size_t prediction;
396 if (diff > max_pending_card_num) {
397 prediction = max_pending_card_num;
398 } else {
399 prediction = max_pending_card_num - diff;
400 }
402 return prediction;
403 }
405 size_t predict_rs_length_diff() {
406 return (size_t) get_new_prediction(_rs_length_diff_seq);
407 }
409 double predict_alloc_rate_ms() {
410 return get_new_prediction(_alloc_rate_ms_seq);
411 }
413 double predict_cost_per_card_ms() {
414 return get_new_prediction(_cost_per_card_ms_seq);
415 }
417 double predict_rs_update_time_ms(size_t pending_cards) {
418 return (double) pending_cards * predict_cost_per_card_ms();
419 }
421 double predict_young_cards_per_entry_ratio() {
422 return get_new_prediction(_young_cards_per_entry_ratio_seq);
423 }
425 double predict_mixed_cards_per_entry_ratio() {
426 if (_mixed_cards_per_entry_ratio_seq->num() < 2) {
427 return predict_young_cards_per_entry_ratio();
428 } else {
429 return get_new_prediction(_mixed_cards_per_entry_ratio_seq);
430 }
431 }
433 size_t predict_young_card_num(size_t rs_length) {
434 return (size_t) ((double) rs_length *
435 predict_young_cards_per_entry_ratio());
436 }
438 size_t predict_non_young_card_num(size_t rs_length) {
439 return (size_t) ((double) rs_length *
440 predict_mixed_cards_per_entry_ratio());
441 }
443 double predict_rs_scan_time_ms(size_t card_num) {
444 if (gcs_are_young()) {
445 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
446 } else {
447 return predict_mixed_rs_scan_time_ms(card_num);
448 }
449 }
451 double predict_mixed_rs_scan_time_ms(size_t card_num) {
452 if (_mixed_cost_per_entry_ms_seq->num() < 3) {
453 return (double) card_num * get_new_prediction(_cost_per_entry_ms_seq);
454 } else {
455 return (double) (card_num *
456 get_new_prediction(_mixed_cost_per_entry_ms_seq));
457 }
458 }
460 double predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) {
461 if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
462 return (1.1 * (double) bytes_to_copy) *
463 get_new_prediction(_cost_per_byte_ms_seq);
464 } else {
465 return (double) bytes_to_copy *
466 get_new_prediction(_cost_per_byte_ms_during_cm_seq);
467 }
468 }
470 double predict_object_copy_time_ms(size_t bytes_to_copy) {
471 if (_in_marking_window && !_in_marking_window_im) {
472 return predict_object_copy_time_ms_during_cm(bytes_to_copy);
473 } else {
474 return (double) bytes_to_copy *
475 get_new_prediction(_cost_per_byte_ms_seq);
476 }
477 }
479 double predict_constant_other_time_ms() {
480 return get_new_prediction(_constant_other_time_ms_seq);
481 }
483 double predict_young_other_time_ms(size_t young_num) {
484 return (double) young_num *
485 get_new_prediction(_young_other_cost_per_region_ms_seq);
486 }
488 double predict_non_young_other_time_ms(size_t non_young_num) {
489 return (double) non_young_num *
490 get_new_prediction(_non_young_other_cost_per_region_ms_seq);
491 }
493 void check_if_region_is_too_expensive(double predicted_time_ms);
495 double predict_young_collection_elapsed_time_ms(size_t adjustment);
496 double predict_base_elapsed_time_ms(size_t pending_cards);
497 double predict_base_elapsed_time_ms(size_t pending_cards,
498 size_t scanned_cards);
499 size_t predict_bytes_to_copy(HeapRegion* hr);
500 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young);
502 void set_recorded_rs_lengths(size_t rs_lengths);
504 size_t cset_region_length() { return young_cset_region_length() +
505 old_cset_region_length(); }
506 size_t young_cset_region_length() { return eden_cset_region_length() +
507 survivor_cset_region_length(); }
509 void record_young_free_cset_time_ms(double time_ms) {
510 _recorded_young_free_cset_time_ms = time_ms;
511 }
513 void record_non_young_free_cset_time_ms(double time_ms) {
514 _recorded_non_young_free_cset_time_ms = time_ms;
515 }
517 double predict_young_gc_eff() {
518 return get_new_neg_prediction(_young_gc_eff_seq);
519 }
521 double predict_survivor_regions_evac_time();
523 void cset_regions_freed() {
524 bool propagate = _last_gc_was_young && !_in_marking_window;
525 _short_lived_surv_rate_group->all_surviving_words_recorded(propagate);
526 _survivor_surv_rate_group->all_surviving_words_recorded(propagate);
527 // also call it on any more surv rate groups
528 }
530 void set_known_garbage_bytes(size_t known_garbage_bytes) {
531 _known_garbage_bytes = known_garbage_bytes;
532 size_t heap_bytes = _g1->capacity();
533 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
534 }
536 void decrease_known_garbage_bytes(size_t known_garbage_bytes) {
537 guarantee( _known_garbage_bytes >= known_garbage_bytes, "invariant" );
539 _known_garbage_bytes -= known_garbage_bytes;
540 size_t heap_bytes = _g1->capacity();
541 _known_garbage_ratio = (double) _known_garbage_bytes / (double) heap_bytes;
542 }
544 G1MMUTracker* mmu_tracker() {
545 return _mmu_tracker;
546 }
548 double max_pause_time_ms() {
549 return _mmu_tracker->max_gc_time() * 1000.0;
550 }
552 double predict_remark_time_ms() {
553 return get_new_prediction(_concurrent_mark_remark_times_ms);
554 }
556 double predict_cleanup_time_ms() {
557 return get_new_prediction(_concurrent_mark_cleanup_times_ms);
558 }
560 // Returns an estimate of the survival rate of the region at yg-age
561 // "yg_age".
562 double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) {
563 TruncatedSeq* seq = surv_rate_group->get_seq(age);
564 if (seq->num() == 0)
565 gclog_or_tty->print("BARF! age is %d", age);
566 guarantee( seq->num() > 0, "invariant" );
567 double pred = get_new_prediction(seq);
568 if (pred > 1.0)
569 pred = 1.0;
570 return pred;
571 }
573 double predict_yg_surv_rate(int age) {
574 return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
575 }
577 double accum_yg_surv_rate_pred(int age) {
578 return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
579 }
581 private:
582 void print_stats(int level, const char* str, double value);
583 void print_stats(int level, const char* str, int value);
585 void print_par_stats(int level, const char* str, double* data);
586 void print_par_sizes(int level, const char* str, double* data);
588 void check_other_times(int level,
589 NumberSeq* other_times_ms,
590 NumberSeq* calc_other_times_ms) const;
592 void print_summary (PauseSummary* stats) const;
594 void print_summary (int level, const char* str, NumberSeq* seq) const;
595 void print_summary_sd (int level, const char* str, NumberSeq* seq) const;
597 double avg_value (double* data);
598 double max_value (double* data);
599 double sum_of_values (double* data);
600 double max_sum (double* data1, double* data2);
602 double _last_pause_time_ms;
604 size_t _bytes_in_collection_set_before_gc;
605 size_t _bytes_copied_during_gc;
607 // Used to count used bytes in CS.
608 friend class CountCSClosure;
610 // Statistics kept per GC stoppage, pause or full.
611 TruncatedSeq* _recent_prev_end_times_for_all_gcs_sec;
613 // Add a new GC of the given duration and end time to the record.
614 void update_recent_gc_times(double end_time_sec, double elapsed_ms);
616 // The head of the list (via "next_in_collection_set()") representing the
617 // current collection set. Set from the incrementally built collection
618 // set at the start of the pause.
619 HeapRegion* _collection_set;
621 // The number of bytes in the collection set before the pause. Set from
622 // the incrementally built collection set at the start of an evacuation
623 // pause.
624 size_t _collection_set_bytes_used_before;
626 // The associated information that is maintained while the incremental
627 // collection set is being built with young regions. Used to populate
628 // the recorded info for the evacuation pause.
630 enum CSetBuildType {
631 Active, // We are actively building the collection set
632 Inactive // We are not actively building the collection set
633 };
635 CSetBuildType _inc_cset_build_state;
637 // The head of the incrementally built collection set.
638 HeapRegion* _inc_cset_head;
640 // The tail of the incrementally built collection set.
641 HeapRegion* _inc_cset_tail;
643 // The number of bytes in the incrementally built collection set.
644 // Used to set _collection_set_bytes_used_before at the start of
645 // an evacuation pause.
646 size_t _inc_cset_bytes_used_before;
648 // Used to record the highest end of heap region in collection set
649 HeapWord* _inc_cset_max_finger;
651 // The RSet lengths recorded for regions in the CSet. It is updated
652 // by the thread that adds a new region to the CSet. We assume that
653 // only one thread can be allocating a new CSet region (currently,
654 // it does so after taking the Heap_lock) hence no need to
655 // synchronize updates to this field.
656 size_t _inc_cset_recorded_rs_lengths;
658 // A concurrent refinement thread periodcially samples the young
659 // region RSets and needs to update _inc_cset_recorded_rs_lengths as
660 // the RSets grow. Instead of having to syncronize updates to that
661 // field we accumulate them in this field and add it to
662 // _inc_cset_recorded_rs_lengths_diffs at the start of a GC.
663 ssize_t _inc_cset_recorded_rs_lengths_diffs;
665 // The predicted elapsed time it will take to collect the regions in
666 // the CSet. This is updated by the thread that adds a new region to
667 // the CSet. See the comment for _inc_cset_recorded_rs_lengths about
668 // MT-safety assumptions.
669 double _inc_cset_predicted_elapsed_time_ms;
671 // See the comment for _inc_cset_recorded_rs_lengths_diffs.
672 double _inc_cset_predicted_elapsed_time_ms_diffs;
674 // Stash a pointer to the g1 heap.
675 G1CollectedHeap* _g1;
677 // The ratio of gc time to elapsed time, computed over recent pauses.
678 double _recent_avg_pause_time_ratio;
680 double recent_avg_pause_time_ratio() {
681 return _recent_avg_pause_time_ratio;
682 }
684 // At the end of a pause we check the heap occupancy and we decide
685 // whether we will start a marking cycle during the next pause. If
686 // we decide that we want to do that, we will set this parameter to
687 // true. So, this parameter will stay true between the end of a
688 // pause and the beginning of a subsequent pause (not necessarily
689 // the next one, see the comments on the next field) when we decide
690 // that we will indeed start a marking cycle and do the initial-mark
691 // work.
692 volatile bool _initiate_conc_mark_if_possible;
694 // If initiate_conc_mark_if_possible() is set at the beginning of a
695 // pause, it is a suggestion that the pause should start a marking
696 // cycle by doing the initial-mark work. However, it is possible
697 // that the concurrent marking thread is still finishing up the
698 // previous marking cycle (e.g., clearing the next marking
699 // bitmap). If that is the case we cannot start a new cycle and
700 // we'll have to wait for the concurrent marking thread to finish
701 // what it is doing. In this case we will postpone the marking cycle
702 // initiation decision for the next pause. When we eventually decide
703 // to start a cycle, we will set _during_initial_mark_pause which
704 // will stay true until the end of the initial-mark pause and it's
705 // the condition that indicates that a pause is doing the
706 // initial-mark work.
707 volatile bool _during_initial_mark_pause;
709 bool _should_revert_to_young_gcs;
710 bool _last_young_gc;
712 // This set of variables tracks the collector efficiency, in order to
713 // determine whether we should initiate a new marking.
714 double _cur_mark_stop_world_time_ms;
715 double _mark_remark_start_sec;
716 double _mark_cleanup_start_sec;
717 double _mark_closure_time_ms;
719 // Update the young list target length either by setting it to the
720 // desired fixed value or by calculating it using G1's pause
721 // prediction model. If no rs_lengths parameter is passed, predict
722 // the RS lengths using the prediction model, otherwise use the
723 // given rs_lengths as the prediction.
724 void update_young_list_target_length(size_t rs_lengths = (size_t) -1);
726 // Calculate and return the minimum desired young list target
727 // length. This is the minimum desired young list length according
728 // to the user's inputs.
729 size_t calculate_young_list_desired_min_length(size_t base_min_length);
731 // Calculate and return the maximum desired young list target
732 // length. This is the maximum desired young list length according
733 // to the user's inputs.
734 size_t calculate_young_list_desired_max_length();
736 // Calculate and return the maximum young list target length that
737 // can fit into the pause time goal. The parameters are: rs_lengths
738 // represent the prediction of how large the young RSet lengths will
739 // be, base_min_length is the alreay existing number of regions in
740 // the young list, min_length and max_length are the desired min and
741 // max young list length according to the user's inputs.
742 size_t calculate_young_list_target_length(size_t rs_lengths,
743 size_t base_min_length,
744 size_t desired_min_length,
745 size_t desired_max_length);
747 // Check whether a given young length (young_length) fits into the
748 // given target pause time and whether the prediction for the amount
749 // of objects to be copied for the given length will fit into the
750 // given free space (expressed by base_free_regions). It is used by
751 // calculate_young_list_target_length().
752 bool predict_will_fit(size_t young_length, double base_time_ms,
753 size_t base_free_regions, double target_pause_time_ms);
755 // Count the number of bytes used in the CS.
756 void count_CS_bytes_used();
758 public:
760 G1CollectorPolicy();
762 virtual G1CollectorPolicy* as_g1_policy() { return this; }
764 virtual CollectorPolicy::Name kind() {
765 return CollectorPolicy::G1CollectorPolicyKind;
766 }
768 // Check the current value of the young list RSet lengths and
769 // compare it against the last prediction. If the current value is
770 // higher, recalculate the young list target length prediction.
771 void revise_young_list_target_length_if_necessary();
773 size_t bytes_in_collection_set() {
774 return _bytes_in_collection_set_before_gc;
775 }
777 unsigned calc_gc_alloc_time_stamp() {
778 return _all_pause_times_ms->num() + 1;
779 }
781 // This should be called after the heap is resized.
782 void record_new_heap_size(size_t new_number_of_regions);
784 void init();
786 // Create jstat counters for the policy.
787 virtual void initialize_gc_policy_counters();
789 virtual HeapWord* mem_allocate_work(size_t size,
790 bool is_tlab,
791 bool* gc_overhead_limit_was_exceeded);
793 // This method controls how a collector handles one or more
794 // of its generations being fully allocated.
795 virtual HeapWord* satisfy_failed_allocation(size_t size,
796 bool is_tlab);
798 BarrierSet::Name barrier_set_name() { return BarrierSet::G1SATBCTLogging; }
800 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; }
802 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
804 // Update the heuristic info to record a collection pause of the given
805 // start time, where the given number of bytes were used at the start.
806 // This may involve changing the desired size of a collection set.
808 void record_stop_world_start();
810 void record_collection_pause_start(double start_time_sec, size_t start_used);
812 // Must currently be called while the world is stopped.
813 void record_concurrent_mark_init_end(double
814 mark_init_elapsed_time_ms);
816 void record_mark_closure_time(double mark_closure_time_ms) {
817 _mark_closure_time_ms = mark_closure_time_ms;
818 }
820 void record_concurrent_mark_remark_start();
821 void record_concurrent_mark_remark_end();
823 void record_concurrent_mark_cleanup_start();
824 void record_concurrent_mark_cleanup_end(int no_of_gc_threads);
825 void record_concurrent_mark_cleanup_completed();
827 void record_concurrent_pause();
828 void record_concurrent_pause_end();
830 void record_collection_pause_end(int no_of_gc_threads);
831 void print_heap_transition();
833 // Record the fact that a full collection occurred.
834 void record_full_collection_start();
835 void record_full_collection_end();
837 void record_gc_worker_start_time(int worker_i, double ms) {
838 _par_last_gc_worker_start_times_ms[worker_i] = ms;
839 }
841 void record_ext_root_scan_time(int worker_i, double ms) {
842 _par_last_ext_root_scan_times_ms[worker_i] = ms;
843 }
845 void record_satb_filtering_time(int worker_i, double ms) {
846 _par_last_satb_filtering_times_ms[worker_i] = ms;
847 }
849 void record_satb_drain_time(double ms) {
850 assert(_g1->mark_in_progress(), "shouldn't be here otherwise");
851 _cur_satb_drain_time_ms = ms;
852 }
854 void record_update_rs_time(int thread, double ms) {
855 _par_last_update_rs_times_ms[thread] = ms;
856 }
858 void record_update_rs_processed_buffers (int thread,
859 double processed_buffers) {
860 _par_last_update_rs_processed_buffers[thread] = processed_buffers;
861 }
863 void record_scan_rs_time(int thread, double ms) {
864 _par_last_scan_rs_times_ms[thread] = ms;
865 }
867 void reset_obj_copy_time(int thread) {
868 _par_last_obj_copy_times_ms[thread] = 0.0;
869 }
871 void reset_obj_copy_time() {
872 reset_obj_copy_time(0);
873 }
875 void record_obj_copy_time(int thread, double ms) {
876 _par_last_obj_copy_times_ms[thread] += ms;
877 }
879 void record_termination(int thread, double ms, size_t attempts) {
880 _par_last_termination_times_ms[thread] = ms;
881 _par_last_termination_attempts[thread] = (double) attempts;
882 }
884 void record_gc_worker_end_time(int worker_i, double ms) {
885 _par_last_gc_worker_end_times_ms[worker_i] = ms;
886 }
888 void record_pause_time_ms(double ms) {
889 _last_pause_time_ms = ms;
890 }
892 void record_clear_ct_time(double ms) {
893 _cur_clear_ct_time_ms = ms;
894 }
896 void record_par_time(double ms) {
897 _cur_collection_par_time_ms = ms;
898 }
900 void record_aux_start_time(int i) {
901 guarantee(i < _aux_num, "should be within range");
902 _cur_aux_start_times_ms[i] = os::elapsedTime() * 1000.0;
903 }
905 void record_aux_end_time(int i) {
906 guarantee(i < _aux_num, "should be within range");
907 double ms = os::elapsedTime() * 1000.0 - _cur_aux_start_times_ms[i];
908 _cur_aux_times_set[i] = true;
909 _cur_aux_times_ms[i] += ms;
910 }
912 void record_ref_proc_time(double ms) {
913 _cur_ref_proc_time_ms = ms;
914 }
916 void record_ref_enq_time(double ms) {
917 _cur_ref_enq_time_ms = ms;
918 }
920 #ifndef PRODUCT
921 void record_cc_clear_time(double ms) {
922 if (_min_clear_cc_time_ms < 0.0 || ms <= _min_clear_cc_time_ms)
923 _min_clear_cc_time_ms = ms;
924 if (_max_clear_cc_time_ms < 0.0 || ms >= _max_clear_cc_time_ms)
925 _max_clear_cc_time_ms = ms;
926 _cur_clear_cc_time_ms = ms;
927 _cum_clear_cc_time_ms += ms;
928 _num_cc_clears++;
929 }
930 #endif
932 // Record how much space we copied during a GC. This is typically
933 // called when a GC alloc region is being retired.
934 void record_bytes_copied_during_gc(size_t bytes) {
935 _bytes_copied_during_gc += bytes;
936 }
938 // The amount of space we copied during a GC.
939 size_t bytes_copied_during_gc() {
940 return _bytes_copied_during_gc;
941 }
943 // Choose a new collection set. Marks the chosen regions as being
944 // "in_collection_set", and links them together. The head and number of
945 // the collection set are available via access methods.
946 void choose_collection_set(double target_pause_time_ms);
948 // The head of the list (via "next_in_collection_set()") representing the
949 // current collection set.
950 HeapRegion* collection_set() { return _collection_set; }
952 void clear_collection_set() { _collection_set = NULL; }
954 // Add old region "hr" to the CSet.
955 void add_old_region_to_cset(HeapRegion* hr);
957 // Incremental CSet Support
959 // The head of the incrementally built collection set.
960 HeapRegion* inc_cset_head() { return _inc_cset_head; }
962 // The tail of the incrementally built collection set.
963 HeapRegion* inc_set_tail() { return _inc_cset_tail; }
965 // Initialize incremental collection set info.
966 void start_incremental_cset_building();
968 // Perform any final calculations on the incremental CSet fields
969 // before we can use them.
970 void finalize_incremental_cset_building();
972 void clear_incremental_cset() {
973 _inc_cset_head = NULL;
974 _inc_cset_tail = NULL;
975 }
977 // Stop adding regions to the incremental collection set
978 void stop_incremental_cset_building() { _inc_cset_build_state = Inactive; }
980 // Add information about hr to the aggregated information for the
981 // incrementally built collection set.
982 void add_to_incremental_cset_info(HeapRegion* hr, size_t rs_length);
984 // Update information about hr in the aggregated information for
985 // the incrementally built collection set.
986 void update_incremental_cset_info(HeapRegion* hr, size_t new_rs_length);
988 private:
989 // Update the incremental cset information when adding a region
990 // (should not be called directly).
991 void add_region_to_incremental_cset_common(HeapRegion* hr);
993 public:
994 // Add hr to the LHS of the incremental collection set.
995 void add_region_to_incremental_cset_lhs(HeapRegion* hr);
997 // Add hr to the RHS of the incremental collection set.
998 void add_region_to_incremental_cset_rhs(HeapRegion* hr);
1000 #ifndef PRODUCT
1001 void print_collection_set(HeapRegion* list_head, outputStream* st);
1002 #endif // !PRODUCT
1004 bool initiate_conc_mark_if_possible() { return _initiate_conc_mark_if_possible; }
1005 void set_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = true; }
1006 void clear_initiate_conc_mark_if_possible() { _initiate_conc_mark_if_possible = false; }
1008 bool during_initial_mark_pause() { return _during_initial_mark_pause; }
1009 void set_during_initial_mark_pause() { _during_initial_mark_pause = true; }
1010 void clear_during_initial_mark_pause(){ _during_initial_mark_pause = false; }
1012 // This sets the initiate_conc_mark_if_possible() flag to start a
1013 // new cycle, as long as we are not already in one. It's best if it
1014 // is called during a safepoint when the test whether a cycle is in
1015 // progress or not is stable.
1016 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
1018 // This is called at the very beginning of an evacuation pause (it
1019 // has to be the first thing that the pause does). If
1020 // initiate_conc_mark_if_possible() is true, and the concurrent
1021 // marking thread has completed its work during the previous cycle,
1022 // it will set during_initial_mark_pause() to so that the pause does
1023 // the initial-mark work and start a marking cycle.
1024 void decide_on_conc_mark_initiation();
1026 // If an expansion would be appropriate, because recent GC overhead had
1027 // exceeded the desired limit, return an amount to expand by.
1028 size_t expansion_amount();
1030 #ifndef PRODUCT
1031 // Check any appropriate marked bytes info, asserting false if
1032 // something's wrong, else returning "true".
1033 bool assertMarkedBytesDataOK();
1034 #endif
1036 // Print tracing information.
1037 void print_tracing_info() const;
1039 // Print stats on young survival ratio
1040 void print_yg_surv_rate_info() const;
1042 void finished_recalculating_age_indexes(bool is_survivors) {
1043 if (is_survivors) {
1044 _survivor_surv_rate_group->finished_recalculating_age_indexes();
1045 } else {
1046 _short_lived_surv_rate_group->finished_recalculating_age_indexes();
1047 }
1048 // do that for any other surv rate groups
1049 }
1051 bool is_young_list_full() {
1052 size_t young_list_length = _g1->young_list()->length();
1053 size_t young_list_target_length = _young_list_target_length;
1054 return young_list_length >= young_list_target_length;
1055 }
1057 bool can_expand_young_list() {
1058 size_t young_list_length = _g1->young_list()->length();
1059 size_t young_list_max_length = _young_list_max_length;
1060 return young_list_length < young_list_max_length;
1061 }
1063 size_t young_list_max_length() {
1064 return _young_list_max_length;
1065 }
1067 bool gcs_are_young() {
1068 return _gcs_are_young;
1069 }
1070 void set_gcs_are_young(bool gcs_are_young) {
1071 _gcs_are_young = gcs_are_young;
1072 }
1074 bool adaptive_young_list_length() {
1075 return _young_gen_sizer->adaptive_young_list_length();
1076 }
1078 inline double get_gc_eff_factor() {
1079 double ratio = _known_garbage_ratio;
1081 double square = ratio * ratio;
1082 // square = square * square;
1083 double ret = square * 9.0 + 1.0;
1084 #if 0
1085 gclog_or_tty->print_cr("ratio = %1.2lf, ret = %1.2lf", ratio, ret);
1086 #endif // 0
1087 guarantee(0.0 <= ret && ret < 10.0, "invariant!");
1088 return ret;
1089 }
1091 private:
1092 //
1093 // Survivor regions policy.
1094 //
1096 // Current tenuring threshold, set to 0 if the collector reaches the
1097 // maximum amount of suvivors regions.
1098 int _tenuring_threshold;
1100 // The limit on the number of regions allocated for survivors.
1101 size_t _max_survivor_regions;
1103 // For reporting purposes.
1104 size_t _eden_bytes_before_gc;
1105 size_t _survivor_bytes_before_gc;
1106 size_t _capacity_before_gc;
1108 // The amount of survor regions after a collection.
1109 size_t _recorded_survivor_regions;
1110 // List of survivor regions.
1111 HeapRegion* _recorded_survivor_head;
1112 HeapRegion* _recorded_survivor_tail;
1114 ageTable _survivors_age_table;
1116 public:
1118 inline GCAllocPurpose
1119 evacuation_destination(HeapRegion* src_region, int age, size_t word_sz) {
1120 if (age < _tenuring_threshold && src_region->is_young()) {
1121 return GCAllocForSurvived;
1122 } else {
1123 return GCAllocForTenured;
1124 }
1125 }
1127 inline bool track_object_age(GCAllocPurpose purpose) {
1128 return purpose == GCAllocForSurvived;
1129 }
1131 static const size_t REGIONS_UNLIMITED = ~(size_t)0;
1133 size_t max_regions(int purpose);
1135 // The limit on regions for a particular purpose is reached.
1136 void note_alloc_region_limit_reached(int purpose) {
1137 if (purpose == GCAllocForSurvived) {
1138 _tenuring_threshold = 0;
1139 }
1140 }
1142 void note_start_adding_survivor_regions() {
1143 _survivor_surv_rate_group->start_adding_regions();
1144 }
1146 void note_stop_adding_survivor_regions() {
1147 _survivor_surv_rate_group->stop_adding_regions();
1148 }
1150 void tenure_all_objects() {
1151 _max_survivor_regions = 0;
1152 _tenuring_threshold = 0;
1153 }
1155 void record_survivor_regions(size_t regions,
1156 HeapRegion* head,
1157 HeapRegion* tail) {
1158 _recorded_survivor_regions = regions;
1159 _recorded_survivor_head = head;
1160 _recorded_survivor_tail = tail;
1161 }
1163 size_t recorded_survivor_regions() {
1164 return _recorded_survivor_regions;
1165 }
1167 void record_thread_age_table(ageTable* age_table)
1168 {
1169 _survivors_age_table.merge_par(age_table);
1170 }
1172 void update_max_gc_locker_expansion();
1174 // Calculates survivor space parameters.
1175 void update_survivors_policy();
1177 };
1179 // This should move to some place more general...
1181 // If we have "n" measurements, and we've kept track of their "sum" and the
1182 // "sum_of_squares" of the measurements, this returns the variance of the
1183 // sequence.
1184 inline double variance(int n, double sum_of_squares, double sum) {
1185 double n_d = (double)n;
1186 double avg = sum/n_d;
1187 return (sum_of_squares - 2.0 * avg * sum + n_d * avg * avg) / n_d;
1188 }
1190 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTORPOLICY_HPP